Need Help!! About to Buy!!!!

[PNW_Steve]

Originally Posted by KevinDarcy11

65 passenger Cummins 5.9 I believe

There are a few folks here with 5.9's in full size buses with either 2000 or 3060's that are happy with them.

I have driven a 72 passenger with the 5.9/3060 and found it to be tollerable but not ideal. That experience helped me decide to hold out for an 8.3 or DT466.

Good luck with your search.

[KevinDarcy11]

As long as everything checks out with the mechanic I think we might bite, fingers crossed!!! Thanks for the help

[Tango]

Once again...remember that an all mechanical 5.9 Cummins can be turned up substantially (HP & torque) without giving up longevity or mpg's. No new parts required.



Is a bigger engine better in a bigger (40') bus...well...ya. But you can come pretty close with a well tuned 5.9.

[cadillackid]

Originally Posted by Tango

Once again...remember that an all mechanical 5.9 Cummins can be turned up substantially (HP & torque) without giving up longevity or mpg's. No new parts required.



Is a bigger engine better in a bigger (40') bus...well...ya. But you can come pretty close with a well tuned 5.9.

Being an old hotrodder.. the Idea of being able to roast the meats on. School bus is becoming more intriguing every day

[PNW_Steve]

I have owned several 5.9's.

My current one makes about 450 HP. I have to disagree that turning up the power significantly does not reduce longevity.

A mild bump may not be a big deal but big bumps come at a price.

"There is no replacement for displacement "

[Ronnie]

Seems the 5.9 was up to around 800ft lbs torque and about 300hp in the Dodge trucks, before going to the 6.7? I would think that would be safe without hurting long term life. 450hp, ok pushing it if you use all of that a lot, in terms of durability.

[Tango]

Keep it within reason and it will simply be a much more efficient engine. Go bonkers on the HP scale and you will indeed pay a price.



For the best tuning info, chat the guys over on 4BTswaps.com (yes...they do more than fours). Some of those guys have been building up these motors for a couple of decades. Lots of savvy there and a great bunch of folks.


I have the basic tuning specs for 4's & 6's. Only difference being what you choose to do with the turbo (if anything) since they are different to begin with. A relatively mild tune with no turbo work can add about 100HP to a 4BT and another 150 or so to a six-banger. And more often than not it also improves mpg's. Sweet!



If anyone is interested, I can post the basic specs.

[Native]

Originally Posted by Tango

I have the basic tuning specs for 4's & 6's. Only difference being what you choose to do with the turbo (if anything) since they are different to begin with. A relatively mild tune with no turbo work can add about 100HP to a 4BT and another 150 or so to a six-banger. And more often than not it also improves mpg's. Sweet!

Any such tweaks for CAT 3126 engines?

[EastCoastCB]

Originally Posted by Native

Any such tweaks for CAT 3126 engines?

Cat software.

[KevinDarcy11]

Good to know. I might send you a message if/when we get it with questions!

[Native]

Originally Posted by EastCoastCB

Cat software.

I was afraid of that. Thanks!


Not afraid, just not ready to invest in the software and electronics at this stage. Of course, I'll eventually want to get an interface to the CAT engine and the Allison transmission. I am reading through Cadillackid's RedByrd thread at present for a little insight.

[EastCoastCB]

Originally Posted by Native

I was afraid of that. Thanks!


Not afraid, just not ready to invest in the software and electronics at this stage. Of course, I'll eventually want to get an interface to the CAT engine and the Allison transmission. I am reading through Cadillackid's RedByrd thread at present for a little insight.

From what I've heard its $350 for a cat dealer to re-rate your engine. Not too bad if you consider how much some people spend on cold air intakes and fart cans.

[cadillackid]

EC - my navistar software shows a couple CAT engines in it.. Iwonder if it will read and program a 3126. even though itsn ot technically one of the "supported" engines listed..



-Christopher

[EastCoastCB]

Originally Posted by cadillackid

EC - my navistar software shows a couple CAT engines in it.. Iwonder if it will read and program a 3126. even though itsn ot technically one of the "supported" engines listed..



-Christopher

That would be too cool! Maybe it does? The 3126 is about as common as medium duty engines get.
Next time I see you maybe we can hook up your gizmos as see what happens?

[cadillackid]

definitely, im guessing if it cant read it, it will just say "cant detect engine".. which is what it does if I connect it up to anything it doesnr recognize..



-Christopher

[EastCoastCB]

Would be cool to see all that data in the bus. Like gallons of fuel consumed and stuff.
And it would be amazing if I could get it bumped from 190 to 210 hp.
I don't think there's a speed limiter, at least below 80 or so.
Will be adding a tranny cooler soon. Getting an Earl's unit from Tango! The main thing I'm hoping for with the cooler is a reduction in temps in the engine's cooling system at higher speeds. Think this will help? I'm planning to run it without a fan and see how it does then add one later.

[Bus ted1]

I agree with PNW Steve about the 5.9. Not all are governed at 55, as mine was set at 65. Also because of the use of this engine in Dodge Trucks there is all sorts of aftermarket support for these engines. It is very easy to raise the power levels substantially on the 12 valve and early 24 valves up to about 2003. After 2003 or so the engines are totally controlled by proprietary computer software and the only method outside factory help is to swap to a early manual fuel control. Easily done. The governed RPM and thus speed is very easily changed.

[cadillackid]

Originally Posted by Bus ted1

I agree with PNW Steve about the 5.9. Not all are governed at 55, as mine was set at 65. Also because of the use of this engine in Dodge Trucks there is all sorts of aftermarket support for these engines. It is very easy to raise the power levels substantially on the 12 valve and early 24 valves up to about 2003. After 2003 or so the engines are totally controlled by proprietary computer software and the only method outside factory help is to swap to a early manual fuel control. Easily done. The governed RPM and thus speed is very easily changed.

while power-adding can be a bit of its own slippery slope.. RPM raising can be an even more slippery slope.. while most of our bus engines may be able to spin faster than they do, doing so is often out of their optimum power band so you actually Lose power not gain it.. though you can gain a few MPH on top end just from too low of final drive ratio...



one of the things to think about is you are taking an engine that has for many years spun at its current top end RPM as the max.. over the years it will have most likely developed a "ring ridge" in the cylinders.. at the spot where the piston travelled the highest..



when you spin an engine up.. the weight of the piston can actually "stretch" the rod slightly and temporarily.. metal reacts to the forces applied and may flex..



for 150k or whatever miles it never spun over that top RPM.. the rod never will have stretched further.



now ad some RPM.. and suddenly your rod stretch is a little greater.. now you are attempting to run the piston up on said ridge... the rings are going to flex .. piston may stop a little faster than it did.. bearings may run in a slightly different position than they did previously etc..



all this sounds minuscule.. but could possibly shorten the life of said engine.. on a fresh rebuild, its much safer to turn up the RPM as all of the parts are fresh and will be broken in with the common Max RPM..





Upping the power is just as slippery of slope.. you can have bearings or other parts which could be weak.. however handled the oriignal power rating.. then you turn it up.. and thuings may wear out quicker or break..





the other thung is to make sure on these engines which were shared amongst Medium duty trucks and pickup trucks to make sure the hardware matches what you want to do... is the 5.9 that you want to make more power and spin faster (because joey down the street did it in his Dodge).. the same engine? or does it differ..



-Christopher

[Tango]

Unless you are a regular at Tractor Pull events, my general recommendation for tuning most diesels is to try and optimize everything around the engines' sweet spot. I'm not a fan of taking the RPM's up by much at all. Remember...one of any diesel engines advantages is the ability to produce power at lower RPM's than most other engine types.



Adjust the timing and fuel flow to get a more torque & hp within about 10% or so of that sweet spot and most engines will reward you with better performance and mpg's because all you have done is improved its' efficiency.


Go pushing the RPM's a bunch and don't be surprised when Cadillac's predictions come true and parts start flying.


Just my dos centavos.